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Aftershock Forecast Sequence-Specific Model Parameters equation 

The probability distribution for the number of aftershocks, P(N), and the forecast can then be computed using the same procedures as for the generic model, using P_seq-spec(a) instead of P_generic(a).

An example of Bayesian updating of productivity parameter (a-value) for the 2010 Mw 8.8 Maule, Chile, earthquake. Immediately following the earthquake, the SZ-GENERIC region-specific a-value distribution can be used.

Screenshot of the Aftershock Forecast for an earthquake in California, showing the information box at the top of the forecast and the four tabs of forecast information.

Equation 2 for the Aftershock Forecast probability distribution to compute the forecast

A low-angle aerial view of the vents where episodic fountaining has been occurring since the start of the ongoing Kīlauea summit eruption on December 23, 2024. A white plume of volcanic gas rises from the north vent (center right) and south vent (center left) cones in the southwest corner of Halema‘uma‘u crater, as viewed during a monitoring overflight.

Icon used to refer to ShakeMap on Product landing pages. For example use, see https://staging-earthquake.usgs.gov/data/pager/background.php.

Two example aftershock sequences, from southern California, that illustrate the three general rules of aftershocks. A circle shows each aftershock's time of occurrence (horizontal axis) and magnitude (vertical axis). The larger-magnitude M6.7 Northridge earthquake is followed by many more aftershocks than the smaller M5.1 La Habra earthquake.

Screenshot of the Aftershock Forecast for an earthquake in California, with the “Summary” tab selected, and “M4+” and “Show All” selections for magnitude and forecast duration.
 

Screenshot of the Aftershock Forecast for an earthquake in California, with the “Summary” tab selected, and “M4+” and “Show All” selections for magnitude and forecast duration.

Screenshot of the Aftershock Forecast for an earthquake in California, with the “Summary” tab selected, scrolled to the bottom of the page. The mainshock is shown with a yellow star on top of its circle; other earthquakes in the forecasting region are also shown colored by time of occurrence.

Aftershock Forecast Model parameters screenshot of the Aftershock Forecast Overview page

Screenshot of the Aftershock Forecast for an earthquake in California, with the “Forecast Table” tab selected.

Screenshot of the Aftershock Forecast for an earthquake in California, with the “Commentary” tab selected.

Screenshot of the Overview webpage for an earthquake in California. The “Aftershock Forecast” card is at lower center.

Screenshot of the Aftershock Forecast for an earthquake in California, with the “Summary” tab selected, and “Show All” and “1 Month” selections for magnitude and forecast duration.

Ven diagram of risk as the intersection of hazards and society. This illustrates the logical relationships between two or more sets of items. 

Tricia Light works with the Natural Hazards Mission Area and has a background in marine chemistry.

Volcanoes tend to have seismicity that waxes and wanes over time. That’s considered normal and not necessarily a cause for concern. Let’s check on Mount Adams to see what USGS scientists are doing to learn more about its recent earthquake activity and what it could mean for this Cascade Range volcano.

LANDSLIDE SAFETY

If your home or property was damaged by a landslide from Hurricane Helene, be aware of the warning signs of future landslide activity

WATCH FOR WARNING SIGNS

Signs a landslide may be moving include:

(a) Photograph of instruments being tested in the East portion of the underground vault. (b) Wench and location of three boreholes in the West portion of the underground vault. (c) Cross-tunnel and recording equipment for the reference sensor vault.

Arial view from the North of the Albuquerque Seismological Laboratory on the Kirtland Air Force Base about 15 miles southeast of Albuquerque, New Mexico.